The use of robotics manipulators has increased drastically over the last few years. For these manipulators to be useful and effective, some means must be provided so that the force being exerted by the manipulator can be sensed and/or controlled.
Many different approaches have been taken to provide the sensing function required for control of the robotics manipulators. These expedients include strain gauges, closed hydraulic systems, hydraulic systems which include pressure sensors, and systems which measure the input force to the manipulator.
The systems in use today tend to be rather complex and costly. In order to make widespread use of robotics, some form of simple, reliable, and inexpensive control systems are necessitated.